1. Field of the Invention
The present invention relates generally to telecommunications systems and more particularly to an improved method and system for preventing fraudulent calls prior to call connection.
2. Description of the Related Art
Telephone fraud is a major area of abuse in the United States and throughout the world. Such fraud frequently involves the unauthorized or bogus use of telephone billing numbers, which have been assigned to customers and are associated with customer billing accounts. These numbers are typically imprinted or encoded on wallet sized cards, which are provided to customers to enable the customers to easily charge calls to their respective billing accounts. Consequently, these numbers are commonly referred to as telephone calling card numbers. As those of ordinary skill in the art will appreciate, however, the terms "calling card number," "billing number" and "bill number" are not restricted to card-based numbers but may refer more generally to any number used to bill or track telecommunications services. Network Configuration and Signaling
A typical telecommunications network is depicted and described in U.S. Pat. No. 5,602,906, which issued on Feb. 11, 1997 in the name of Phelps, for a toll fraud detection system ("the Phelps patent.") The Phelps patent, which is assigned to the assignee of the present invention, is expressly incorporated herein by reference.
Generally, a telecommunications network includes telephone units interconnected to each other via central offices owned by local exchange carriers (LECs). These central offices are in turn interconnected to each other via network equipment owned by long distance service providers, or interexchange carriers (IXCs). The LEC provides local switches for receiving and forwarding calls placed to and from the interconnected telephone units as well as a tandem switch for passing calls between the local switches and the IXC. The IXC in turn includes switches designed to receive and forward calls to and from the LECs and from point to point throughout the IXC's long distance network.
In order to establish a communication path for connecting a given call, an IXC network typically provides a signaling system. The signaling system allows network elements such as switches to exchange information regarding the routing of telecommunications traffic over network connections. For example, the signaling system might transfer a dialed number from switch to switch so that each switch along the call path can process the dialed number and select connections for the call. A well known example of a signaling system is Signaling System #7 (SS7).
In most cases, the IXC network includes a service control point (SCP), which serves to process signaling messages transmitted throughout the network. The SCP is typically coupled to the IXC switches over signaling links and through signaling transfer points (STPs), which allow the SCP to exchange signaling messages with the switches.
When a switch or other network system (such as an operator assistance center, for instance) requires routing additional information to facilitate completion of a particular call, it will usually transmit a signaling message to an SCP, requesting the additional information. This message is commonly known as a transaction capabilities application part (TCAP) message and identifies information specific to the call, such as caller number (known as ANI), dialed number and calling card number.
The SCP serves primarily to validate customer information and to provide routing information to the querying system, based on information contained in the TCAP message. An example of this mechanism is disclosed, for instance, in U.S. Pat. No. 5,694,463, entitled "System for Service Control Point Routing" (the '463 patent), which issued on Dec. 2, 1997. The '463 patent is assigned to the owner of the present invention and is expressly incorporated herein by reference.
As described in the '463 patent, when the SCP receives a TCAP, it checks the format of the message and then performs customer validation. To validate customer information, the SCP refers to one or more validation databases that contain a list of customer information. As known by those skilled in the art, this information may provide a negative list of calling card numbers blocked or "stunned" from use. Alternatively, other configurations are also possible. Based on this validation process, the SCP returns a response TCAP message to the querying system, indicating either that the call may proceed or that the call should be treated as blocked.
If the SCP validates the customer information associated with the proposed call, the SCP then retrieves a corresponding customer record from the database. The customer record is typically identified by information in the TCAP message and includes a routing tree identification (ID). The SCP uses this routing tree ID to access a customer's particular routing plan and particularly to identify a connection to which the switch should route the call for the particular customer.
More specifically, as further described by the '463 patent, the SCP may include a routing tree structure that defines routing information for a given call. The routing tree consists of a series of "decision nodes," each of which is defined by a database table that contains particular criteria and yields a predetermined result. The routing tree produces a determination of where to route the call, in the form of a trunk and switch combination. The SCP in turn places these connection identifiers in a response TCAP message for return transmission to the querying system. Finally, upon receipt of this response TCAP message, the switch or other requesting element routes the call as instructed.
The Need for Fraud Prevention
Fraudulent use of calling card numbers has evolved over the years and has unfortunately responded to telephone company detection efforts. As interexchange carriers have developed new systems to detect and prevent fraud, criminals have developed new tactics for defeating those very detection schemes.
In an early form, for instance, calling card fraud was detected by customers or long distance service providers who recognized the existence of unauthorized charges on customer billing statements. In response, interexchange carriers developed systems for monitoring records of completed calls, in search of aberrations or telltale signs of fraud. In turn, however, criminals developed methods of maximizing their fraudulent use of card numbers before the calls are completed. For example, organized groups of criminals have arranged to simultaneously or serially make multiple calls from phones across the country using a single stolen calling card number. As another example, criminals have used stolen card numbers to make expensive overseas calls that last many hours at a time and that evade detection until completed.
The process of preventing calling card fraud has typically involved analyzing a history of abuse in order to identify trends, and thereby formulating rules for responding to similar events in the future. Frequently, such systems detect fraud primarily based on generic calling patterns for a given calling card. For instance, the IXC may employ a fraud management system that regularly receives call records from the SCP and automatically applies thresholds developed from historical fraud patterns associated with previously abused cards and account history. If the call satisfies a sufficient threshold, the fraud management system may instruct the SCP to block subsequent calls that use the card number. Typically, the SCP would then include the blocked calling card number in a database for reference in the validation process described above.
In other instances, history may reveal a need to prevent the connection of calls from certain areas to certain destinations. For example, reports may identify that certain payphones in New York have repeatedly been the source of fraudulent calling card calls to Guadalajara, Mexico. Existing systems have responded to this situation by configuring the associated IXC switches to prevent such calls from being connected. For example, those skilled in the art are aware that Northern Telecom manufactures a DMS-250 switch, that may include a table of international restrictions to be tested for each attempted call. One such restriction, for instance, may preclude any calls destined for Guadalajara, Mexico.
Unfortunately, however, adding such call processing logic to the switch can be inefficient and expensive, for several reasons. First, the IXC may not directly administer its switches and may require the assistance of others (such as the switch vendor, for instance) to implement new preconnect fraud rules in the switches. Second, a typical IXC network includes numerous switches (on the order of 30-40 in an illustrative network). Consequently, the IXC may need to reconfigure hardware or software in all of its switches in order to implement the desired change. For instance, if the IXC determines that calls to Guadalajara, Mexico are typically fraudulent, the IXC would need to include an appropriate indication in every switch in its network. Absent such measures, criminals would undoubtedly find the "unprotected" switch and continue their crimes. At the same time, of course, this protection scheme will unfortunately prevent some legitimate billing number calls from connecting to blocked countries.
Telecommunications fraud has subjected interexchange carriers to financial loss, in part because the charges for such calls are frequently uncollectible. This is especially the case with international calls, because the interexchange carrier handling the call may have to transfer payments to the destination telephone company, even if the toll charge is uncollectible.
Further, the effects of telecommunications fraud have extended to others as well. For instance, interexchange carriers may sell long distance service to local exchange carriers or other companies that act as apparent "long distance service providers" to callers. An LEC, for instance, may establish its "own" long distance service for its customers by arranging for an interexchange carrier to supply the service and providing its customers with calling cards. By arrangement with the IXC, these calling cards may be associated with specific platforms in the IXC's switches to define custom logic for processing calls made with the cards.
Fraudulent use of such LEC calling card numbers may not only affect the interexchange carrier that actually provides the service, but may also affect customer perception of the local company that issues the cards. In some circumstances, these companies as well as the associated IXC may in turn suffer financial loss as a result of such calling card fraud.
In view of these deficiencies in the art, a need exists for a more efficient and intelligent system of preventing telecommunications fraud.